The present invention relates to a light absorptive antireflector and a process for its production.
Heretofore, antireflection and shielding of electromagnetic waves for e.g. a screen portion of a display, have been accomplished by laminating a low refractive index dielectric film, a high refractive index dielectric film and a high refractive index conductive film which are substantially transparent to visible light, from a substrate side (JP-A-60-168102). However, with an antireflection film of such a multilayer structure, it has been necessary to increase the number of layers constituting the antireflection film in order to broaden the wavelength range for low reflection, and there has been a problem that the production cost increases accordingly.
Further, a double layer antireflection film having a light absorptive film and a silica film laminated from a substrate side (DE3942990) has been proposed as one wherein the film structure has been simplified to accomplish the above-mentioned antireflection and shielding of electromagnetic waves. However, even if this light absorptive antireflection film of double layer structure comprising a light absorptive film such as a titanium nitride layer, and a silica film, was employed, the wavelength range for low reflection, of the obtainable light absorptive antireflector, was narrow, and the antireflection characteristics were inadequate.
It is an object of the present invention to provide a light absorptive antireflector which exhibits adequate antireflection characteristics with a simple layer structure, and a process for its production.
Another object of the present invention is to provide a light absorptive antireflector excellent in heat resistance with a simple layer structure, and a process for its production.
The present invention provides a light absorptive antireflector which comprises a substrate, and a titanium oxy-nitride film having a geometrical film thickness of from 5 to 25 nm and a film composed mainly of silica and having a geometrical film thickness of from 70 to 130 nm formed in this order on the substrate, to reduce reflection of incident light from the side of the film composed mainly of silica, wherein the ratio in the number of atoms of oxygen to titanium in said titanium oxy-nitride is from 0.11 to 0.33 (hereinafter referred to as the first invention).
Further, the present invention provides a light absorptive antireflector which comprises a substrate, and a titanium oxy-nitride film having a geometrical film thickness of from 15 to 30 nm, a dielectric film having a geometrical film thickness of from 10 to 30 nm and a refractive index of at least 1.7 and being substantially transparent to visible light, and a film composed mainly of silica and having a geometrical film thickness of from 50 to 90 nm formed in this order on the substrate, to reduce reflection of incident light from the side of the film composed mainly of silica, wherein the ratio in the number of atoms of oxygen to titanium in said titanium oxy-nitride is from 0.11 to 0.33 (hereinafter referred to as the second invention).